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Sedna May Have A Moon
ArrayIndexOutOfBound writes "The newly found planet Sedna may have a moon. It appears that most astronomers argue that Sedna is only another proof that neither Sedna nor Pluto are really planets.
Interestingly, the planet has been found by an 'automated sky survey telescope'..."
SYSS Mouse points to a NASA page with more information about "our potential 10th planet. ... It is 130 billion miles away from the sun (900 times Earth's distance from the sun) and has a 10,500 years orbit, compared to Pluto's 230 years around the sun."
Um, the article said it was 13 billion miles out, not 130 billion (now discovering something that size 130 billion miles out would be a real hell of an achievement :)
There's some theorizing that this may be part of the inner Oort shell; I think it more likely that at that distance it's an outer member of the Kuiper bodies.
Given the highly elliptical orbit, it's size, and it's apparently odd surface color, it's also possible that it's a body captured by the sun some hundreds of millions or billions of years ago. Now *that'd* be neat.
SB
It's old. The more humans I meet, the more I like my cats. At least they are honest.
The first link is about an object named "2004 DW". The second link is about Sedna (previous known as 2003 VB12).
The newly found moon is orbiting Sedna, NOT 2004 DW.
The links in the slashdot article are misleading.
From the same page:
Is Sedna an Oort Cloud Comet?
From the Classical Oort Cloud - no. The latter consists of objects whose orbits are so large (50,000 AU) that passing stars and galactic tides can alter their properties. Sedna doesn't travel very far out (1000 AU) and is effectively immune to external forces. Also, the inclinations of both Sedna and 2000 CR105 are small (12 and 23 degrees, respectively). These objects know where the plane of the solar system lies. Oort Cloud orbits are random with inclinations all the way up to 180 degrees.
So What Is It?
Sedna could be a member of a substantial population of bodies trapped between the Kuiper Belt and Oort Cloud. These would have been emplaced at early times and unseen until recently. 2000 CR105 and Sedna are "just the tip of the iceberg", as they say. The scientific interest lies in how these objects had their perihelia lifted out of the planetary region.
So it's really on the fuzzy boundary between the two, but closer to the Kuiper belt than to traditional Oort cloud objects. I'd bet there are a lot more objects this close to this size out there. (a hunch, but we're only beginning to explore that region).
Fascinating. I wonder if we'll ever trace it's orbit back far enough to determine whether it was flung out of the inner system or formed elsewhere. Doubtful. In any case, it's good to know there are objects this size out in that region, just in case we ever *really* need to flee the inner system (tongue in cheek, partially; reading the news gives me that feeling often nowadays..)
SB
It's old. The more humans I meet, the more I like my cats. At least they are honest.
I thought it was a misprint in the article, so I went to Nature news. Sure enough at perihelion it is 13 billion km from the Sun an at aphelion it is 130 billion km. Wow, usually you only see orbits that eccentric with comets. Which makes it seem more like a captured object rather than one that formed in orbit. Wonder white kind of perturbing influence it has on comets in the Kuiper Belt, admittedly its small and in a very big volume ... still ...
Bitter and proud of it.
Many (non-planet) Asteroids have moons or satellites in orbit about them..
"You lied to me! There is a Swansea!"
Kuiper Belt Objects are about half and half rock and ice, actually. Beyond about 5 AU you expect icey bodies, since hydrogen compounds are way more common than metals and silicates. (The only trouble being that it has to be cool enough for them to condense.)
And, yes, there has long been hypothesized to be (based on dynamical models and, I believe, comet distributions) an Inner and Outer Oort Cloud.
There is some thought that the Inner Oort Cloud should sort of merge with the Edgeworth-Kuiper Belt, although that's mostly speculation.
Since the Edgeworth-Kuiper Belt is thought to stop around 50 AU or so, this object isn't likely to be a KBO. Inner Oort Cloud seems to fit, though.
Orbital inclinations which are retrograde are considered to be greater than 90 degrees
SB
It's old. The more humans I meet, the more I like my cats. At least they are honest.
Atmospheric (or lens) diffraction, I'd say. If you were out in space, you could probably block it out with the tip of a pin.
More info on this here.
Why would anyone engrave "Elbereth"?
Yes, but if Voyager 2 were to encounter Sedna now, it wouldn't do a bit of good. It doesn't have nearly enough power to collect any useful data, let alone return it. Both Voyagers and Pioneers 10 and 11 have been essentially comatose for many years now: they're alive, but just barely.